Dielectric compositions for firing at low temperatures and electronic parts

ABSTRACT

An object of the present invention is to provide a dielectric composition for firing at a low temperature having a high dielectric constant ∈ r, a high Q value, and a low temperature coefficient τ f of the resonance frequency. A dielectric composition for firing at low temperatures comprises a main composition of x.BaO-y.TiO 2 -z1.Nd 2 O 3 -z2.La 2 O 3 -z3.Sm 2 O 3 -t.Bi 2 O 3  (x+y+z 1+z 2+z 3+t=1 ; 0.070≦x≦0.300; 0.385≦y ≦0.844; 0.010≦z1≦0.130; 0.000≦z2≦0.120; 0.000≦z3≦0.120; 0.075&lt;t≦0.185), and a glass component containing 0.1 weight percent or more of B 2 O 3  in an amount of 0.05 to 20 weight parts with respect to 10 weight parts of the main composition.

[0001] This application claims the benefits of Japanese Patent Applications P2003-56718, filed on Mar. 4, 2003, and 2003-420051, filed on Dec. 17, 2003, the entireties of which are incorporated by reference.

BACKGROUND OF THE INVENTION

[0002] 1. Field of the Invention

[0003] The present invention relates to a low temperature-fired porcelain having a high dielectric constant ∈ r and to an electronic part using such porcelain.

[0004] 2. Related Art Statement

[0005] In high frequency circuit radio instruments such as cellular phones, top filters, interstage filters, local filters, etc. are used as high frequency circuit filters, and a laminated type dielectric filter is used as an interstage filter.

[0006] In order to produce a dielectric-laminated filter, a plurality of green sheets are produced from a powdery ceramic material to constitute a dielectric, and a given electrode pattern is formed on each of the green sheets by printing with a given conductive paste. A laminate is then obtained by laminating the resulting green sheets, and the laminate is fired so that the conductive paste layers and the green sheets are simultaneously fired to densify the laminate.

[0007] At that time a metallic conductor having a low melting point, such as a silver-based conductor, a copper-based conductor or a nickel-based conductor is generally used for the electrode. The melting points are, for example, 1100° C. or lower. Ag has a melting point of about 950to 960° C. For this reason, the dielectric needs to be sintered at a firing temperature lower than the melting point of the metal constituting the electrode.

[0008] The assignee has disclosed a dielectric composition for firing at a low temperature in Japanese patent publication H5-319922A.

SUMMARY OF THE INVENTION

[0009] It has recently been demanded to further miniaturize electronic parts and thus to further improve the dielectric constant ∈ r of a dielectric porcelain composition. For example, the lower limit of dimensions of a dielectric laminate filter obtainable is 2.0 mm×1.25 mm when the dielectric composition having a dielectric constant of 80. When a dielectric porcelain composition having a dielectric constant of 110 or higher is used, the lower limits of the dimensions of the filter can be reduced to 1.6 mm×0.8 mm.

[0010] An object of the present invention is to provide a dielectric composition for firing at a low temperature having a high dielectric constant ∈ r, a high Q value, and a low temperature coefficient τ f of resonance frequency.

[0011] A first aspect of the present invention provides a dielectric composition for firing at low temperatures comprising a main composition of x.BaO-y.TiO₂-z1.Nd₂O₃-z2. La₂O₃-z3.Sm₂O₃-t.Bi₂O₃ (x+y +z1+z2+z3+t=1; 0.070≦x≦0.300; 0.385≦y≦0.844; 0.010≦z1 ≦0.130; 0.000≦z2≦0.120; 0.000≦z3≦0.120; 0.075<t≦0.185), and a glass component containing 0.1 weight percent or more of B₂O₃ in an amount of 0.05 to 20 weight parts with respect to 100 weight parts of the main composition.

[0012] A second aspect of the present invention further provides a dielectric composition for firing at low temperatures comprising a main composition of x.BaO-y.TiO₂-z1.Nd₂O₃-z2.La₂O₃-z3.Sm₂O₃-t.Bi₂O₃ (x+y+z1+z2+z3+t=1; 0.070≦x≦0.300; 0.385≦y≦0.844; 0.010≦z1≦0.130; 0.000≦z2 ≦0.120; 0.000≦z3≦0.120; 0.075<t≦0.185) and B₂O₃ in an amount of 0.05 to 10 weight parts with respect to 100 weight parts of the main composition.

[0013] The first and second aspects are the same in the main compositions.

[0014] A third aspect of the present invention provides a dielectric composition for firing at low temperatures comprising a main composition of x.BaO-y.TiO₂-z1.Nd₂O₃-z2.La₂O₃-z3.Sm₂O₃-t.Bi₂O₃ (x+y+z1+z2+z3+t=1; 0.100≦x≦0.250; 0.600≦y≦0.750; 0.010≦z1≦0.120; 0.000≦z2≦0.120; 0.000≦z3≦0.120; 0.010≦(z1+z2+z3)≦0.120; 0.065≦t≦0.075; 0.35≦t/(z1+z2+z3+t), and a glass component containing 0.1 weight percent or more of B₂O₃ in an amount of 0.05 to 20 weight parts with respect to 100 weight parts of the main composition.

[0015] A fourth aspect of the present invention provides a dielectric composition for firing at low temperatures comprising a main composition of x.BaO-y.TiO₂-z1.Nd₂O₃-z2.La₂O₃-z3.Sm₂O₃-t.Bi₂O₃(x+y +z1+z2+z3+t=1; 0.100≦x≦0.250; 0.600≦y≦0.750 ; 0.010≦z1 ≦0.120; 0.000≦z2≦0.120; 0.000≦z3≦0.120; 0.010≦(z1+z2+z3)≦0.120;0.065≦t≦0.075; 0.35≦t/(z1+z2+z3+t) and B₂O₃ in an amount of 0.05 to 10 weight parts with respect to 100 weight parts of the main composition.

[0016] The third and fourth aspects are the same in the main compositions.

[0017] The present invention further provides an electronic part having each of the dielectric compositions for firing at a low temperature according to the first to fourth aspects of the present invention.

[0018] The present invention provides a dielectric composition for firing at a low temperature having a high dielectric constant (∈ r), a high Q value, τ f (a low temperature coefficient of resonance frequency), and can be produced by firing at a low temperature. Typically, the dielectric constant ∈ r can be improved to 110 or more, Q can be improved to 200 or more, and the absolute value of τ f can be reduced to 50 or lower.

[0019] These and other objects, features and advantages of the invention will be appreciated upon reading the following description of the invention when taken in conjunction with the attached drawings, with the understanding that some modifications, variations and changes of the same could be made by the skilled person in the art.

Preferred Embodiments of the Invention

[0020] The main compositions are the same with each other in the first and second aspects of the invention, and will be described as follows.

[0021] The ratio “x” of BaO is made 0.070 or higher and 0.300 or lower in the main composition. The dielectric constant ∈ r can be improved by increasing “x” to 0.070 or higher. On the viewpoint, “x” is made 0.070 or higher and may preferably be 0.100 or higher. The “Q” value can be improved and τ f can be reduced by lowering “x” to 0.300 or lower. On the viewpoint, “x” is made 0.300 or lower, and may preferably be 0.250 or lower.

[0022] The ratio “y” of TiO₂ is made 0.385 or higher and 0.844 or lower in the main composition. The “Q” value can be improved and τ f can be reduced by increasing “y” to 0.385 or higher. On the viewpoint, “y” is made 0.385 or higher, and may preferably be 0.390 or higher. The dielectric constant ∈ r can be improved by reducing “y” to 0.844 or lower. On the viewpoint, “y” is made 0.844 or lower and may preferably be 0.800 or lower.

[0023] The ratio “z1” of Nd₂O₃ is made 0.010 or higher and 0.130 or lower. The dielectric constant ∈ r can be improved by adjusting “z1” at a value in a range of 0.010 to 0.130. On the viewpoint, “z1” may preferably be 0.030 or higher and is 0.130 or lower.

[0024] The ratio “t” of Bi₂O₃ is made higher than 0.075 and 0.185 or lower in the main composition. The dielectric constant ∈ r can be improved by increasing “x” to a value exceeding 0.075. On the viewpoint, “t” may preferably be 0.0751 or higher and more preferably be 0.076 or higher. Further, the “Q” value can be improved and τ f can be reduced by lowering “t” to 0.185 or lower. On the viewpoint, “t” is made 0.185 or lower, and may preferably be 0.160 or lower.

[0025] The ratio “z2” of La₂O₃ is made 0.120 or lower. The dielectric constant ∈ r can be further improved by adding La₂O₃. Further, the “Q” value can be improved and τ f can be reduced by lowering “z2” to 0.120 or lower. On the viewpoint, “z2” is made 0.120 or lower, and may preferably be 0.100 or lower.

[0026] The ratio “z3” of Sm₂O₃ is made 0.120 or lower. The dielectric constant ∈ r and the “Q” value can be improved and τ f can be reduced by adding Sm₂O₃ in an amount of 0.120 or lower. On the viewpoint, “z3” is made 0.120 or lower, and may preferably be 0.100 or lower.

[0027] The main compositions are the same with each other in the third and fourth aspects of the invention, and will be described as follows.

[0028] The ratio “x” of BaO is made 0.100 or higher and 0.250 or lower in the main composition. The dielectric constant ∈ r can be improved by increasing “x” to 0.100 or higher. On the viewpoint, “x” may preferably be 0.150 or higher. The “Q” value can be improved and τ f can be reduced by lowering “x” to 0.250 or lower. On the viewpoint, “x” may preferably be 0.200 or lower.

[0029] The ratio “y” of TiO₂ is made 0.600 or higher and 0.750 or lower in the main composition. The “Q” value can be improved and τ f can be reduced by increasing “y” to 0.600 or higher. On the viewpoint, “y” may preferably be 0.640 or higher. The dielectric constant ∈ r can be improved by reducing “y” to 0.750 or lower. On the viewpoint, “y” may preferably be 0.720 or lower.

[0030] The ratio “z1” of Nd₂O₃ is made 0.010 or higher and 0.120 or lower. The dielectric constant ∈ r can be improved by reducing “z1” to 0.120 or lower. τ f can be reduced by increasing “z1” to 0.010 or higher. “z1” may preferably be 0.030 or higher.

[0031] The ratio “z2” of La₂O₃ is made 0.120 or lower. The dielectric constant ∈ r can be further improved by adding La₂O₃. The “Q” value can be improved and τ f can be reduced by reducing “z2” to 0.120 or lower.

[0032] The ratio “z3” of Sm₂O₃ is made 0.120 or lower. The “Q” value and the dielectric constant ∈ r can be improved and τ f can be reduced by adding Sm₂O₃ in an amount of 0.120 or lower.

[0033] (z1+z2+z3) is made 0.010 or higher and 0.120 or lower, so that the dielectric constant ∈ r can be improved.

[0034] The ratio “t” of Bi₂O₃ is made 0.065 or higher and 0.075 or lower in the main composition. It is found that the dielectric constant ∈ r can be improved only when t/(z1+z2+z3) is 0.35 or higher, provided that “t” is 0.75 or lower. It is further found that the Q value is lowered when “t” is lower than 0.065, provided that t/(z1+z2+z3) is 0.35 or higher. It is also found that the dielectric constant ∈ r is reduced when t/(z1+z2+z3) is lower than 0.35, provided that “t” is in a range of 0.065 to 0.075.

[0035] According to the first and third aspects of the present invention, a glass component containing 0.1 weight percent or more of B₂O₃ is mixed to the main composition in an amount of 0.05 to 20 weight parts with respect to 100 weight parts of the main composition. The porcelain can be obtained by sintering at a low temperature by adding 0.1 weight percent or more of B₂O₃ into the glass component.

[0036] The content of the glass component is made 0.05 weight parts or higher, so that the dielectric constant ∈ r of the porcelain can be further improved. On the viewpoint, the content of the glass component is made 0.05 weight parts or higher and may preferably be 0.10 weight parts or higher. Further, the dielectric constant ∈ r can be improved by reducing the content of the glass component to 20.0 weight parts or lower. On the viewpoint, the content of the glass component is made 20.00 weight parts or lower, and may preferably be 15.00 weight parts or lower.

[0037] The glass component is not particularly limited and may preferably be one or more of the followings.

[0038] ZnO—B₂O₃—SiO₂, ZnO—Bi₂O₃—B₂O₃—SiO₂, B₂O₃—SiO₂RO—B₂O₃—SiO₂ (R represents an alkali earth metal) GeO₂—B₂O₃ GeO₂—B₂O₃ —SiO₂ GeO₂—ZnO—B₂₃—SiO₂ GeO₂—ZnO—B₂O₃ Li₂O—Al₂O₃—SiO₂—B₂O₃ Li₂O—Al₂O₃—SiO₂—ZnO—B₂O₃ RO—Li₂O—Al₂O₃—SiO₂—B₂O₃ (R represents an alka earth metal) RO—Li₂O—Al₂O₃—SiO₂—ZnO—B₂O₃ (R represents an alkali earth metal) Re₂O—B₂O₃—SiO₂ (Re represents an alkali metal) Re₂O—B₂O₃—ZnO—SiO₂ (Re represents an alkali metal), Re₂O—RO—B₂O₃—SiO₂ glass (Re represents an alkali metal and R represents an alkali earth metal), and Re₂O—RO—B₂O₃—ZnO—SiO₂ glass (Re represents an alkali metal and R represents an alkali earth metal)

[0039] In a preferred embodiment, the glass component has a composition of ZnO—B₂O₃—SiO₂ where k(weight %) ZnO.m(weight %) B₂O₃.n(weight %) SiO₂ (10≦k≦85, 5≦m≦50, 2≦n≦60; k+m+n=100).

[0040] In the above composition, the vitrifaction of the composition can be proceeded by increasing the content (k) of ZnO to 10 weight percent or higher. On the viewpoint, “k” is made 10 weight percent or higher and may preferably be 20 weight percent or higher. Further, the vitrifaction of the composition can be proceeded and the optimum firing temperature of the dielectric porcelain composition can be reduced by increasing “k” to 85 weight percent or higher. On the viewpoint, “k” is made 85 weight percent or lower, and may preferably be 80 weight percent or lower.

[0041] The vitrifaction of the composition can be proceeded and the dielectric constant ∈ r can be improved by increasing the content (m) of B₂O₃ to 5 weight percent or higher. On the viewpoint, “m” is made 5 weight percent or higher, and may preferably be 10 weight percent or higher. Further, Q can be reduced by lowering “m” to 50 weight percent or lower. On the viewpoint, “m” is made 50 weight percent or lower, and may preferably be 45 weight percent or lower.

[0042] A glass having stable properties can be produced by adding SiO₂ in a content “n” of 2 weight percent or higher. On the viewpoint, “n” may preferably be 5 weight percent or higher. On the other hand, the vitrifaction of the composition can be proceeded and sintering temperature of the dielectric porcelain composition can be reduced by adding SiO₂ in a content “n” of 60 weight percent or lower.

[0043] According to the second and fourth aspects of the present invention, 0.05 weight parts or higher and 10 weight parts or lower of B₂O₃ is added in the main composition with respect to 100 weight parts of the main composition. The dielectric constant ∈ r and Q value can be improved by adding B₂O₃ in a content of 0.05 weight parts or higher. On the viewpoint, the content of B₂O₃ is made 0.05 weight parts or higher, and may preferably be 0.1 weight parts or higher. Further, the dielectric constant ∈ r and Q value can be improved by adding B₂O₃ in a content of 10 weight parts or lower, and may preferably be 9 weight parts or lower.

[0044] In the first to fourth aspects of the present invention, each of the ratios “x”, “y”, “z1”, “z2”, “z3” and “t” of the metal oxide components is a converted value of a content of each metal contained in the corresponding raw material calculated as a content of the metal oxide. The converted value of the content of each metal in a mixture of the raw materials is dependent on a mixed ratio of the raw materials. According to the present invention, the mixed ratio of the raw materials for metals is weighed using a precision balance to obtain a measured ratio, so that the converted contents are then calculated based on the measured ratio.

[0045] The main compositions and glass components of the dielectric porcelain compositions according to the first to fourth aspects of the invention has been described above. The other metal element or elements may be contained in the compositions.

[0046] For example, the dielectric composition may contain one or more metal selected from the group consisting of Ag, Cu and Ni in a total amount of 5 weight percent or lower. It is thus possible to further reduce τ f.

[0047] The dielectric composition may contain one or more metal oxide selected from the group consisting of CuO, V₂O₅ and WO₃. In this case, a total content of the metal oxides may preferably be 0.0 to 5.0 weight percent.

[0048] The dielectric composition may further contain at lease one of the oxides of Mg, Al, Si, Ca, Sc, Fe, Co, Ni, Zn, Ga, Se, Sr, Y, Zr, Nb, Mo, Ru, Hf and Mn in a total content of 5 weight percent or lower.

[0049] The materials for a metal electrode used in the electronic part according to the invention is not particularly limited. Such material may preferably be silver, copper, nickel, or the alloys of these metals, more preferably be silver or the alloy of silver, and most preferably be silver.

[0050] The electronic parts targeted by the first to fourth aspects of the present invention are not particularly limited, but laminated dielectric filters, multi-layered circuit boards, dielectric antennas, dielectric couplers, dielectric composite modules, bulk type dielectric filters etc. are recited by way of example.

[0051] The dielectric composition for firing at a low temperature may be sintered at a temperature of 1100° C. or lower, more preferably be 1050° C. or lower, and most preferably 1000° C. or lower.

[0052] The porcelains according to the first to fourth aspects of the present invention may preferably be produced as follows. Starting materials for the respective metal components are mixed in a given ratio to obtain a mixed powder. The powder is then calcined at 1000 to 1400° C. to obtain a calcined powder, which is then crushed to obtain ceramic powder. Preferably, a green sheet is formed by using the ceramic powder and a glass powder composed of SiO₂, B₂O₃ and ZnO, and the green sheet is fired at 850 to 930° C. As the starting materials for the respective metallic oxide components, an oxide, a nitrate, a carbonate, a sulfate or the like of each of the metals may be used.

EXAMPLES Experiment 1

[0053] (Production of Powder of the Main Composition)

[0054] Powdery raw materials of barium carbonate, titanium oxide, neodymium oxide, bismuth oxide, lanthanum oxide and samarium oxide each having a high purity were weighed in given ratios shown in tables 2, 3 and 4 to obtain mixed powder. The mixed powder was charged into a polyethylene pot with alumina medium and water was added to wet mix the powder. The thus obtained mixture was drawn from the pot, dried, and charged into an alumina crucible to calcine the mixture at various temperatures of 900 to 1270° C. for 4 hours under air to obtain a calcined body.The calcined body was crushed, charged into a polyethylene pot with zirconia medium and ground until the mean grain diameter is reduced to 0.1 to 2.0 μm measured by laser diffraction scattering method to obtain various kinds of calcined and crushed compositions.

[0055] (Production of Glass Powder)

[0056] Powdery raw materials of zinc oxide, boron oxide and silicon oxide each having a high purity were weighed according to ratios shown in table 1 and mixed to obtain mixed powder. The mixed powder was then charged into a polyethylene pot with alumina medium and dry mixed. The thus obtained mixture was molten in a chamotte crucible, and rapidly cooled by immersing it into water to proceed the vitrifaction. The thus obtained glass was charged in an alumina pot with alumina medium and then ground until the mean grain diameter is reduced to 4 μm in ethanol to obtain each glass powder shown in table 1. TABLE 1 Glass Composition No. ZnO B₂O₃ SiO₂ A1  0.10 0.45 0.45 A2  0.20 0.40 0.40 A3  0.50 0.29 0.21 A4  0.70 0.15 0.15 A5  0.80 0.10 0.10 A6  0.85 0.05 0.10 A7  0.60 0.05 0.35 A8  0.40 0.10 0.50 A9  0.20 0.20 0.60 A10 0.35 0.30 0.35 A11 0.15 0.45 0.40 A12 0.20 0.50 0.30 A13 0.75 0.23 0.02 A14 0.45 0.50 0.05 A15 0.30 0.40 0.30 A16 0.30 0.20 0.50 A17 0.25 0.20 0.55 A18 0.35 0.05 0.60

[0057] (Production of Porcelain)

[0058] The main composition powder and glass powder as described above were formulated as shown in tables 2 to 4. The formulates were charged in a polyethylene pot with alumina medium and water was added for wet mixing. 1 weight percent, of polyvinyl alcohol was added as a binder to the mixture with respect to a total weight of the powder of the main component and glass powder. The thus obtained mixture was dried and passed through a sieve having a mesh diameter of 355 μm and granulated. “Glass contents” shown in tables 2, 3 and 4 were the contents of the glass component with respect to 100 weight parts of the main composition.

[0059] The thus obtained granulated powder was shaped using a press molding machine at a bearing stress of 1 ton/cm² to obtain a disk shaped test piece having a diameter φ of 20 mm and a thickness of 15 mm. The thus obtained test piece was sintered for 2 hours at 900° C. in air to produce various samples of the dielectric porcelains. Further, the thus sintered samples were ground to a disk having a diameter φ of 16 mm and a thickness of 8 mm, and the dielectric properties were measured. The dielectric constant (∈ r) and Q were measured by parallel conductor type dielectric resonator method, and the temperature coefficient (τ f) of resonance frequency was measured in a range of −25° C. to 75° C. The measurements were performed at a frequency of 2 to 4 GHz. The results were shown in tables 2, 3 and 4. TABLE 2 Main Glass composition y: z1: t: z2: z3: Composition Content No. x: BaO TiO2 Nd2O3 Bi2O3 La2O3 Sm2O3 No. of glass εr Q(at3 GHz) τf B1  0.050 0.797 0.063 0.090 0.000 0.000 A3 2.5 wt % 108 357 36 B2  0.070 0.800 0.053 0.077 0.000 0.000 A3 2.5 wt % 110 405 28 B3  0.100 0.752 0.070 0.078 0.000 0.000 A3 2.5 wt % 113 380 30 B4  0.200 0.660 0.060 0.080 0.000 0.000 A3 2.5 wt % 124 242 37 B5  0.250 0.620 0.051 0.079 0.000 0.000 A3 2.5 wt % 128 236 39 B6  0.300 0.600 0.024 0.076 0.000 0.000 A3 2.5 wt % 130 230 41 B7  0.320 0.584 0.020 0.076 0.000 0.000 A3 2.5 wt % 150 124 256 B8  0.423 0.380 0.097 0.100 0.000 0.000 A3 2.5 wt % 149 153 67 B9  0.300 0.385 0.130 0.185 0.000 0.000 A3 2.5 wt % 143 205 48 B10 0.300 0.390 0.130 0.180 0.000 0.000 A3 2.5 wt % 141 209 47 B11 0.146 0.584 0.120 0.150 0.000 0.000 A3 2.5 wt % 135 221 44 B12 0.200 0.600 0.110 0.090 0.000 0.000 A3 2.5 wt % 136 218 46 B13 0.120 0.750 0.050 0.080 0.000 0.000 A3 2.5 wt % 118 310 33 B14 0.071 0.800 0.053 0.076 0.000 0.000 A3 2.5 wt % 111 409 29 B15 0.070 0.844 0.011 0.075 0.000 0.000 A3 2.5 wt % 110 410 28 B16 0.064 0.850 0.010 0.076 0.000 0.000 A3 2.5 wt % 89 430 25

[0060] TABLE 3 Main Glass Composition x: y: z1: t: z2: z3: Composition Content No. BaO TiO2 Nd2O3 Bi2O3 La2O3 Sm2O3 No. of Glass εr Q(at3 GHz) τf B17 0.194 0.724 0.005 0.077 0.000 0.000 A3 2.5 wt % 113 175 63 B18 0.180 0.700 0.010 0.110 0.000 0.000 A3 2.5 wt % 126 238 39 B19 0141 0.750 0.030 0.079 0.000 0.000 A3 2.5 wt % 120 249 35 B20 0.170 0.684 0.070 0.076 0.000 0.000 A3 2.5 wt % 123 245 37 B21 0.170 0.570 0.110 0.150 0.000 0.000 A3 2.5 wt % 132 226 42 B22 0.190 0.600 0.130 0.080 0.000 0.000 A3 2.5 wt % 124 242 37 B23 0.153 0.623 0.140 0.084 0.000 0.000 A3 2.5 wt % 106 262 29 B25 0160 0.695 0.0698 0.0752 0.000 0.000 A3 2.5 wt % 110 300 28 B26 0.160 0.695 0.0695 0.0755 0.000 0.000 A3 2.5 wt % 115 28 30 B27 0.160 0.695 0.069 0.076 0.000 0.000 A3 2.5 wt % 120 260 34 B28 0.180 0.660 0.083 0.077 0.000 0.000 A3 2.5 wt % 122 247 36 B29 0.171 0.640 0.089 0.100 0.000 0.000 A3 2.5 wt % 134 222 43 B30 0.170 0.580 0.090 0.160 0.000 0.000 A3 2.5 wt % 142 208 48 B31 0.165 0.600 0.050 0.185 0.000 0.000 A3 2.5 wt % 143 205 49 B32 0.154 0.580 0.076 0.190 0.000 0.000 A3 2.5 wt % 147 183 58

[0061] TABLE 4 Main Glass Composition x: y: z1: t: z2: z3: Composition Content No. BaO TiO2 Nd2O3 Bi2O3 La2O3 Sm2O3 No. of Glass εr Q(at3 GHz) τf B33 0.150 0.720 0.030 0.090 0.000 0.010 A3 2.5 wt % 129 232 41 B34 0.140 0.690 0.040 0.100 0.020 0.010 A3 2.5 wt % 128 234 42 B35 0.170 0.660 0.020 0.080 0.050 0.020 A3 2.5 wt % 132 225 42 B36 0.160 0.570 0.040 0.080 0.100 0.050 A3 2.5 wt % 132 225 42 B37 0.200 0.490 0.030 0.100 0.120 0.060 A3 2.5 wt % 142 208 47 B38 0.125 0.537 0.052 0.076 0.140 0.070 A3 2.5 wt % 151 126 89 B39 0.120 0.680 0.090 0.100 0.010 0.000 A3 2.5 wt % 118 310 33 B40 0.170 0.590 0.080 0.130 0.010 0.020 A3 2.5 wt % 140 211 48 B41 0.180 0.600 0.050 0.090 0.030 0.050 A3 2.5 wt % 128 245 40 B42 0.090 0.610 0.030 0.100 0.070 0.100 A3 2.5 wt % 118 305 33 B43 0.070 0.550 0.040 0.120 0.100 0.120 A3 2.5 wt % 129 239 40 B44 0.120 0.495 0.096 0.079 0.070 0.140 A3 2.5 wt % 105 290 39

[0062] As shown in table 2, the dielectric constant ∈ r can be improved by increasing the ratio “x” of BaO to 0.070 or higher. Further, the Q value can be improved and τ f can be reduced by lowering “x” to 0.300 or lower.

[0063] As shown in table 2, the Q value can be improved and τ f can be reduced by increasing the ratio “y” of TiO₂ to 0.385 or higher. Further the dielectric constant ∈ r can be improved by reducing “y” to 0.844 or lower.

[0064] As shown in table 3, the dielectric constant ∈ r can be improved by increasing the ratio “z1” of Nd₂O₃ to 0.010 to 0.130.

[0065] As shown in table 3, the dielectric constant ∈ r can be improved by increasing the ratio “t” of Bi₂O₃ to a value exceeding 0.075. Further the Q value can be improved and τ f can be reduced by lowering “t” to 0.185 or lower.

[0066] As shown in table 4, the dielectric constant ∈ r can be further improved by adding La₂O₃. Further, the Q value can be improved and τ f can be reduced by reducing “z2” to 0.120 or lower.

[0067] As shown in table 4, the dielectric constant ∈ r and the Q value can be improved and τ f can be reduced by adding Sm₂O₃ in an amount of 0.120 or lower.

Experiment 2

[0068] Porcelains were produced according to the same process as the experiment 1 and the properties were measured as the experiment 1. Compositions A1 to A18 of the glass components were shown in table 1. The ratios of the metal elements and glass compositions were shown in tables 5 and 6. The results obtained by using the glass compositions A1 to A14 were shown in table 5, and the results obtained by using the glass compositions A15 to A18 were shown in table 6. TABLE 5 Main Glass Composition x: y: z1: t: z2: z3: Composition Content No. BaO TiO2 Nd2O3 Bi2O3 La2O3 Sm2O3 No. of Glass εr Q(at3 GHz) τf B4  0.200 0.660 0.060 0.080 0.000 0.000 A1 2.5 wt % 128 232 40 B12 0.200 0.600 0.110 0.090 0.000 0.000 A2 2.5 wt % 130 230 41 B20 0.170 0.684 0.070 0.076 0.000 0.000 A3 2.5 wt % 123 245 37 B28 0.180 0.660 0.085 0.075 0.000 0.000 A4 2.5 wt % 122 245 40 B35 0.170 0.660 0.020 0.080 0.050 0.020 A5 2.5 wt % 125 242 39 B41 0.180 0.600 0.050 0.090 0.030 0.050 A6 2.5 wt % 129 234 40 B4  0.200 0.660 0.060 0.080 0.000 0.000 A7 2.5 wt % 125 245 38 B12 0.200 0.600 0.110 0.090 0.000 0.000 A8 2.5 wt % 124 243 37 B20 0170 0.684 0.070 0.076 0.000 0.000 A9 2.5 wt % 122 246 37 B28 0.180 0.660 0.085 0.075 0.000 0.000  A10 2.5 wt % 123 244 37 B35 0.170 0.660 0.020 0.080 0.050 0.020  A11 2.5 wt % 125 241 38 B41 0.180 0.600 0.050 0.090 0.030 0.050  A12 2.5 wt % 124 242 37 B4  0.200 0.660 0.060 0.080 0.000 0.000  A13 2.5 wt % 124 243 38 B12 0.200 0.600 0.110 0.090 0.000 0.000  A14 2.5 wt % 126 238 39

[0069] TABLE 6 Main Glass Composition x: y: z1: t: z2: z3: Composition Content No. BaO TiO2 Nd2O3 Bi2O3 La2O3 Sm2O3 No. of Glass εr Q(at3 GHz) τf B20 0.170 0.684 0.070 0.076 0.000 0.000  A15  2.5 wt % 124 242 37 B28 0.180 0.660 0.085 0.075 0.000 0.000  A16  2.5 wt % 122 252 36 B35 0.170 0.660 0.020 0.080 0.050 0.020  A17  2.5 wt % 121 248 37 B41 0.180 0.600 0.050 0.090 0.030 0.050  A18  2.5 wt % 120 250 34 B20 0.170 0.684 0.070 0.076 0.000 0.000 A3  0.01 wt % 82 120 59 B20 0.170 0.684 0.070 0.076 0.000 0.000 A3  0.05 wt % 115 330 31 B20 0.170 0.684 0.070 0.076 0.000 0.000 A3  0.10 wt % 118 295 34 B20 0.170 0.684 0.070 0.076 0.000 0.000 A3  1.00 wt % 120 248 35 B20 0.170 0.684 0.070 0.076 0.000 0.000 A3  2.50 wt % 123 245 37 B20 0.170 0.684 0.070 0.076 0.000 0.000 A3  5.00 wt % 123 246 38 B20 0.170 0.684 0.070 0.076 0.000 0.000 A3 10.00 wt % 120 245 36 B20 0.170 0.684 0.070 0.076 0.000 0.000 A3 15.00 wt % 115 329 33 B20 0.170 0.684 0.070 0.076 0.000 0.000 A3 20.00 wt % 110 290 29 B20 0.170 0.684 0.070 0.076 0.000 0.000 A3 25.00 wt % 91 200 31

[0070] As can be seen from tables 5 and 6, the dielectric constant ∈ r and Q values can be improved and τ f can be reduced by using the glass compositions according to the present invention.

Experiment 3

[0071] Porcelains were produced according to the same process as the experiment 1 and the properties were measured as the experiment 1. The glass composition A3 was used and the ratio or the ingredients was changed as shown in table 6. As can be seen from the results, the dielectric constant ∈ r and Q values can be improved and τ f can be reduced by adjusting the glass content to 0.05 to 20.00 weight percent.

Experiment 4

[0072] Porcelains were produced according to the same process as the experiment 1 and the properties were measured as the experiment 1. The glass composition was changed as shown in table 7 and the ratio of metal oxides and glass composition were changed as shown in table 8. As can be seen from the results, the dielectric constant ∈ r and Q values can be improved and τ f can be reduced in a range of the present invention. TABLE 7 Composition No. Composition system A19 ZnO—B2O3—SiO2 glass A20 ZnO—Bi2O3—B2O3—SiO2 glass A21 B2O3—SiO2 glass A22 RO—B2O3—SiO2 glass (R represents an alkali earth metal) A23 GeO2—B2O3 glass A24 GeO2—B2O3—SiO2 glass A25 GeO2—ZnO—B2O3—SiO2 glass A26 GeO2—ZnO—B2O3 glass A27 Li2O—Al2O3—SiO3—B2O3 glass A28 Li2O—Al2O3—SiO3—ZnO—B2O3 glass A29 RO—Li2O—Al2O3—SiO3—B2O3 glass (R represents an alkali earth metal) A30 RO—Li2O—Al2O3—SiO3—ZnO—B2O3 glass (R represents an alkali earth metal) A31 Re2O—B2O3—SiO2 glass (Re represents an alkali metal) A32 Re2O—B2O3—ZnO—SiO2 glass (Re represents an alkali metal) A33 Re2O—RO—B2O3—SiO2 glass (Re represents an alkali metal: R represents an alkali earth metal) A34 Re2O—RO—B2O3—ZnO—SiO2 glass (Re represents an alkali metal; R represents an alkali earth metal)

[0073] TABLE 8 Main Glass Composition x: y: z1: t: z2: z3: Composition Content No. BaO TiO2 Nd2O3 Bi2O3 La2O3 Sm2O3 No. of glass εr Q(at3 GHz) τf B20 0.170 0.684 0.070 0.076 0.000 0.000 A19 2.5 wt % 126 239 38 B20 0.170 0.684 0.070 0.076 0.000 0.000 A20 2.5 wt % 124 243 36 B20 0.170 0.684 0.070 0.076 0.000 0.000 A21 2.5 wt % 125 242 37 B20 0.170 0.684 0.070 0.076 0.000 0.000 A22 2.5 wt % 126 237 39 B20 0.170 0.684 0.070 0.076 0.000 0.000 A23 2.5 wt % 126 239 38 B20 0.170 0.684 0.070 0.076 0.000 0.000 A24 2.5 wt % 123 248 36 B20 0.170 0.684 0.070 0.076 0.000 0.000 A25 2.5 wt % 125 239 38 B20 0.170 0.684 0.070 0.076 0.000 0.000 A26 2.5 wt % 126 243 39 B20 0.170 0.684 0.070 0.076 0.000 0.000 A27 2.5 wt % 127 231 40 B20 0.170 0.684 0.070 0.076 0.000 0.000 A28 2.5 wt % 129 230 40 B20 0.170 0.684 0.070 0.076 0.000 0.000 A29 2.5 wt % 128 238 39 B20 0.170 0.684 0.070 0.076 0.000 0.000 A30 2.5 wt % 124 241 37 B20 0.170 0.684 0.070 0.076 0.000 0.000 A31 2.5 wt % 123 246 37 B20 0.170 0.684 0.070 0.076 0.000 0.000 A32 2.5 wt % 125 240 37 B20 0.170 0.684 0.070 0.076 0.000 0.000 A33 2.5 wt % 126 239 39 B20 0.170 0.684 0.070 0.076 0.000 0.000 A34 2.5 wt % 128 231 40

Experiment 5

[0074] Porcelains were produced according to the same process as the experiment 1 and the properties were measured as the experiment 1. Bi₂O₃ was added as the glass component and the content was changed as shown in table 9. The composition of the metal oxides was also changed as shown in table 9. As a result, the dielectric constant ∈ r and Q values can be improved and τ f can be reduced by adding 0.01 weight percent or more of Bi₂O₃. TABLE 9 Main Glass Composition x: y: z1: t: z2: z3: Composition Content No. BaO TiO2 Nd2O3 Bi2O3 La2O3 Sm2O3 No. of glass εr Q(at3 GHz) τf B20 0.170 0.684 0.070 0.076 0.000 0.000 A3  0.01 wt % 110 205 38 B20 0.170 0.684 0.070 0.076 0.000 0.000 A3  0.10 wt % 116 212 39 B20 0.170 0.684 0.070 0.076 0.000 0.000 A3  1.00 wt % 120 226 37 B20 0.170 0.684 0.070 0.076 0.000 0.000 A3  2.50 wt % 126 239 38 B20 0.170 0.684 0.070 0.076 0.000 0.000 A3  5.00 wt % 125 242 38 B20 0.170 0.684 0.070 0.076 0.000 0.000 A3 10.00 wt % 121 238 38

Experiment 6

[0075] Porcelains were produced according to the same process as the experiment 1 and the properties were measured as the experiment 1. The glass composition A3 was used in a content of 1.5 weight percent. The ratio of metal oxides was changed as shown in table 10. Silver, copper and nickel was added to the main component as shown in table 10. TABLE 10 Main Compo- Content of Q sition x: y: Z1: t: z2: z3: Glass Content Additional Additional (at 3 No. BaO TiO2 Nd2O3 Bi2O3 La2O3 Sm2O3 Composition of glass Component Component εr GHz) τf B20 0.170 0.684 0.070 0.076 0.000 0.000 A3 1.5 wt % Ag 0.0 wt % 123 245 37 B20 0.170 0.684 0.070 0.076 0.000 0.000 A3 1.5 wt % Ag 0.5 wt % 126 230 38 B20 0.170 0.684 0.070 0.076 0.000 0.000 A3 1.5 wt % Ag 2.5 wt % 124 220 37 B20 0.170 0.684 0.070 0.076 0.000 0.000 A3 1.5 wt % Ag 5.0 wt % 120 210 35 B20 0.170 0.684 0.070 0.076 0.000 0.000 A3 1.5 wt % Ag 7.5 wt % 109 190 63 B20 0.170 0.684 0.070 0.076 0.000 0.000 A3 1.5 wt % Cu 0.0 wt % 123 245 37 B20 0.170 0.684 0.070 0.076 0.000 0.000 A3 1.5 wt % Cu 0.5 wt % 126 230 37 B20 0.170 0.684 0.070 0.076 0.000 0.000 A3 1.5 wt % Cu 2.5 wt % 125 220 34 B20 0.170 0.684 0.070 0.076 0.000 0.000 A3 1.5 wt % Cu 5.0 wt % 122 205 32 B20 0.170 0.684 0.070 0.076 0.000 0.000 A3 1.5 wt % Cu 7.5 wt % 108 188 62 B20 0.170 0.684 0.070 0.076 0.000 0.000 A3 1.5 wt % Ni 0.0 wt % 123 245 37 B20 0.170 0.684 0.070 0.076 0.000 0.000 A3 1.5 wt % Ni 0.5 wt % 126 235 39 B20 0.170 0.684 0.070 0.076 0.000 0.000 A3 1.5 wt % Ni 2.5 wt % 125 220 38 B20 0.170 0.684 0.070 0.076 0.000 0.000 A3 1.5 wt % Ni 5.0 wt % 122 210 36 B20 0.170 0.684 0.070 0.076 0.000 0.000 A3 1.5 wt % Ni 7.5 wt % 109 189 63

[0076] As a result, the dielectric constant ∈ r and Q value can be improved and τ f can be reduced when silver, copper or nickel was added to the main composition.

Experiment 7

[0077] Porcelains were produced according to the same process as the experiment 1 and the properties were measured as the experiment 1. The glass composition A3 was used in a content of 1.5 weight percent. The ratio of metal oxides was changed as shown in table 10. Copper oxide, vanadium oxide or tungsten oxide was added to the main component as shown in table 11. TABLE 11 Main Compo- Content of Q nent x: y: Z1: t: z2: z3: Glass Content Additional Additional (at 3 No. BaO TiO2 Nd2O3 Bi2O3 La2O3 Sm2O3 Composition of glass Component Component εr GHz) τf B20 0.170 0.684 0.070 0.076 0.000 0.000 A3 1.5 wt % CuO 0.0 wt % 123 245 37 B20 0.170 0.684 0.070 0.076 0.000 0.000 A3 1.5 wt % CuO 0.5 wt % 126 320 39 B20 0.170 0.684 0.070 0.076 0.000 0.000 A3 1.5 wt % CuO 2.5 wt % 125 270 38 B20 0.170 0.684 0.070 0.076 0.000 0.000 A3 1.5 wt % CuO 5.0 wt % 123 230 36 B20 0.170 0.684 0.070 0.076 0.000 0.000 A3 1.5 wt % CuO 7.5 wt % 107 168 10 B20 0.170 0.684 0.070 0.076 0.000 0.000 A3 1.5 wt % V2O5 0.0 wt % 123 245 37 B20 0.170 0.684 0.070 0.076 0.000 0.000 A3 1.5 wt % V2O5 0.5 wt % 128 290 39 B20 0.170 0.684 0.070 0.076 0.000 0.000 A3 1.5 wt % V2O5 2.5 wt % 126 250 39 B20 0.170 0.684 0.070 0.076 0.000 0.000 A3 1.5 wt % V2O5 5.0 wt % 124 220 37 B20 0.170 0.684 0.070 0.076 0.000 0.000 A3 1.5 wt % V2O5 7.5 wt % 105 143 68 B20 0.170 0.684 0.070 0.076 0.000 0.000 A3 1.5 wt % WO3 0.0 wt % 123 245 37 B20 0.170 0.684 0.070 0.076 0.000 0.000 A3 1.5 wt % WO3 0.5 wt % 130 240 41 B20 0.170 0.684 0.070 0.076 0.000 0.000 A3 1.5 wt % WO3 2.5 wt % 127 230 40 B20 0.170 0.684 0.070 0.076 0.000 0.000 A3 1.5 wt % WO3 5.0 wt % 125 210 37 B20 0.170 0.684 0.070 0.076 0.000 0.000 A3 1.5 wt % WO3 7.5 wt % 107 183 67

[0078] As a result, the dielectric constant ∈ r and Q value can be improved and τ f can be reduced when copper oxide, vanadium oxide or tungsten oxide was added to the main composition.

Experiment 8

[0079] Porcelains were produced according to the same process as the experiment 1 and the properties were measured as the experiment 1. The glass composition A3 was used in a content of 2.5 weight percent. The ratio of metal oxides was changed as shown in tables 12 and 13. The results were shown in tables 12 and 13. TABLE 12 Main Compo- z1 + Glass Content Q τf sition x: y: Z1: z2: z3: Z2 + t: Composition of Glass (at ppm/ No. BaO TiO2 Nd2O3 La2O3 Sm2O3 Z3 a Bi2O3 No. (wt, %) εr 3 GHz) ° C. C1 Comparative 0.090 0.750 0.088 0.000 0.000 0.088 0.450 0.072 A3 2.5 107 305 23 Example C2 Example 0.137 0.680 0.110 0.000 0.000 0.110 0.400 0.073 A3 2.5 112 295 34 C3 Example 0.176 0.660 0.090 0.000 0.000 0.090 0.450 0.074 A3 2.5 126 278 38 C4 Example 0.160 0.715 0.050 0.000 0.000 0.050 0.600 0.075 A3 2.5 130 259 41 C5 Example 0.245 0.657 0.030 0.000 0.000 0.030 0.695 0.068 A3 2.5 132 227 49 C6 Example 0.245 0.657 0.030 0.000 0.000 0.030 0.695 0.068 A3 2.5 138 213 54 C7 Comparative 0.260 0.600 0.080 0.000 0.000 0.080 0.427 0.060 A3 2.5 123 190 60 Example C8 Comparative 0.226 0.580 0.120 0.000 0.000 0.120 0.380 0.074 A3 2.5 122 194 54 Example C9 Comparative 0.100 0.770 0.065 0.000 0.000 0.065 0.500 0.065 A3 2.5 108 297 27 Example

[0080] TABLE 13 Main Glass Content Q τf Composition x: y: z1: z2: z3: z1 + z2 + t: Composition Of glass (at ppm/ No. BaO TiO2 Nd2O3 La2O3 Sm2O3 Z3 a Bi2O3 No. wt. % εr 3 GHz) ° C. C10 Comparative 0.180 0.620 0.130 0.000 0.000 0.130 0.350 0.070 A3 2.5 106 227 44 Example C11 Comparative 0.225 0.704 0.005 0.000 0.000 0.005 0.930 0.066 A3 2.5 112 224 96 Example C12 Comparative 0.200 0.720 0.056 0.000 0.000 0.056 0.300 0.024 A3 2.5 106 248 30 Example C13 Example 0.116 0.730 0.080 0.000 0.000 0.080 0.480 0.074 A3 2.5 112 282 28 C14 Example 0.167 0.666 0.020 0.080 0.000 0.100 0.400 0.067 A3 2.5 117 244 39 C15 Example 0.175 0.650 0.030 0.000 0.070 0.100 0.430 0.075 A3 2.5 127 241 43 C16 Example 0.215 0.630 0.020 0.020 0.050 0.090 0.420 0.065 A3 2.5 122 213 50 C17 Comparative 0.205 0.707 0.000 0.022 0.000 0.022 0.750 0.066 A3 2.5 124 237 72 Example C18 Comparative 0.185 0.668 0.080 0.015 0.015 0.110 0.250 0.037 A3 2.5 105 240 33 Example

[0081] In the composition No. C1, the ratio “x” of BaO was low so that the dielectric constant ∈ r was reduced. In composition numbers C2 to C6, the dielectric constant ∈ r and Q can be improved and the temperature coefficient (τ f ) of resonance frequency can be maintained at a low value. In number C7, the ratio “x” of BaO was large and the ratio “t” of Bi₂O₃ was low so that Q can be reduced. In number C8, the ratio “y” of TiO₂ was low so that Q was lowered. In number C9, the ratio “y” of TiO₂ was high, so that the dielectric constant ∈ r was reduced. In number C10, (z1+z2+z3) was high so that the dielectric constant ∈ r was lowered. In number C11, the ratio “z1” of Nd₂O₃ was low so that the temperature coefficient (τ f) of resonance frequency was large. In number C12, a/(z1+z2+z3) was low and the ratio “t” of Bi₂O₃ was low, so that the dielectric constant ∈ r was reduced. In numbers C13 to C16, the dielectric constant ∈ r and Q can be improved and the temperature coefficient (τ f) of resonance frequency can be maintained at a low value. In number C17, the ratio “z1” of Nd₂O₃ was low so that the temperature coefficient (τ f) of resonance frequency was large. In number C18, a/(z1+z2+z3) and the ratio “t” of Bi₂O₃ were low, so that the dielectric constant ∈ r was lowered.

[0082] As described above, the present invention provides a dielectric composition for firing at a low temperature having a high dielectric constant ∈ r, a high Q value and a low temperature coefficient τ f of resonance frequency.

[0083] The present invention has been explained referring to the preferred embodiments, however, the present invention is not limited to the illustrated embodiments which are given by way of examples only, and may be carried out in various modes without departing from the scope of the invention. 

1. A dielectric composition for firing at low temperatures comprising a main composition of x.BaO—y.TiO₂-z1.Nd₂O₃-z2.La₂O₃ —z3.Sm₂O₃-t.Bi₂O₃ (x+y+z1+z2+z3+t=1; 0.070≦x≦0.300; 0.385≦-y≦0.844; 0.010≦z1≦0.130; 0.000≦z2≦0.120; 0.000≦z3≦0.120; 0.075≦t≦0.185), and a glass component containing 0.1 weight percent or more of B₂O₃ in an amount of 0.05 to 20 weight parts with respect to 100 weight parts of said main composition.
 2. The dielectric composition of claim 1, wherein said glass component is selected from the group consisting of the following compositions. ZnO—B₂O₃—SiO₂ ZnO—Bi₂O₃—B₂O₃—SiO₂ B₂O₃—SiO₂ RO—B₂O₃—SiO₂ (R represents an alkali earth metal) GeO₂—B₂O₃ GeO₂—B₂O₃ —SiO₂ GeO₂—ZnO—B₂O₃—SiO₂ GeO2—ZnO—B₂O—Li₂O—Al₂O₃—SiO₂—B₂O₃ Li₂O—Al₂O₃—SiO₂—ZnO—B₂O₃ RO—Li₂O—Al₂O₃—SiO₂—B₂O₃ (R represents an alkali earth metal) RO—Li₂O—Al₂O₃—SiO₂—ZnO—B₂O₃ (R represents an alkali earth metal) Re₂O—B₂O₃—SiO₂ (Re represents an alkali metal) Re₂O—B₂O₃—ZnO—SiO₂ (Re represents an alkali metal) Re₂O—RO—B₂O₃—SiO₂ glass (Re represents an alkalimetal and R represents an alkali earth metal) and Re₂O—RO—B₂O₃—ZnO—SiO₂ glass (Re represents an alkali metal and R represents an alkali earth metal)
 3. The dielectric composition of claim 2, wherein said glass component comprises a glass component of ZnO—B₂O₃—SiO₂ having a composition of k (weight %) ZnO.m(weight %) B₂O₃.n (weight %) SiO₂(10≦k≦85, 5≦m≦50, 2≦n≦60; k+m+n=100).
 4. The dielectric composition of claim 1, comprising one or more metal element selected from the group consisting of Ag, Cu and Ni in a total amount of 5 weight percent or lower.
 5. The dielectric composition of claim 1, comprising one or more metal oxide selected from the group consisting of CuO, V₂O₅ and WO₃.
 6. An electronic part comprising said dielectric composition of claim
 1. 7. The electronic part of claim 6 being a laminate type dielectric filter
 8. A dielectric composition for firing at low temperatures comprising a main composition of x.BaO-y.TiO₂-z1.Nd₂O₃-z2.La₂O₃-z3.Sm₂O₃-t.Bi₂O₃ (x+y+z1+z2+z3+t=1; 0.070≦x ≦0.385≦y≦0.844; 0.010≦z1≦0.130; 0.000≦z2≦0.120; 0.000≦z3≦0.120; 0.075≦t≦0.185) and B₂O₃ in an amount of 0.05 to 10 weight parts with respect to 100 weight parts of said main composition.
 9. The dielectric composition of claim 8, comprising one or more metal element selected from the group consisting of Ag, Cu and Ni in a total amount of 5 weight percent or lower.
 10. The dielectric composition of claim 8, comprising one or more metal oxide selected from the group consisting of CuO, V₂O₅ and WO₃.
 11. An electronic part comprising said dielectric composition of claim
 8. 12. The electronic part of claim 11 being a laminate type dielectric filter
 13. A dielectric composition for firing at low temperatures comprising a main composition of x.BaO-y.TiO₂-z1.Nd₂O₃-z2.La₂O₃-z3.Sm₂O₃-t.Bi₂O₃ (x+y+z1+z2+z3+t=1; 0.100≦x≦0.250; 0.600≦y≦0.750; 0.010≦z1≦0.120; 0.000≦z2≦0.120; 0.000≦z3≦0.120; 0.010≦(z1+z2+z3)≦0.120; 0.065≦t≦0.075; 0.35≦t/(z1+z2+z3+t), and a glass component containing 0.1 weight percent or more of B₂O₃ in an amount of 0.05 to 20 weight parts with respect to 100 weight parts of said main composition.
 14. The dielectric composition of claim 13, wherein said glass component is selected from the group consisting of the following compositions. ZnO—B₂O₃—SiO₂ ZnO—Bi₂O₃—B₂O₃—SiO₂ B₂O₃—SiO₂ RO—B₂O₃—SiO₂ (R represents an alkali earth metal) GeO₂—B₂O₃ GeO₂—B₂O₃—SiO₂ GeO₂—ZnO—B₂O₃—SiO₂ GeO₂—ZnO—B₂O₃ Li₂O—Al₂O₃—SiO₂—B₂O₃ Li₂O—Al₂O₃—SiO₂—ZnO—B₂O₃ RO—Li₂O—Al₂O₃—SiO₂—B₂O₃ (R represents an alkali earth metal) RO—Li₂O—Al₂O₃—SiO₂—ZnO—B₂O₃ (R represents an alkali earth metal) Re₂O—B₂O₃—SiO₂ (Re represents an alkali metal) Re₂O—B₂O₃—ZnO—SiO₂ (Re represents an alkali metal) Re₂O—RO—B₂O₃—SiO₂ glass (Re represents an alkali metal and R represents an alkali earth metal) and Re₂O—RO—B₂O₃—ZnO—SiO₂ glass (Re represents an alkali metal and R represents an alkali earth metal)
 15. The dielectric composition of claim 14, wherein said glass component comprises a glass component of ZnO—B₂O₃—SiO₂ having a composition of k (weight %) ZnO .m(weight %) B₂O₃. n(weight %) SiO₂ (10≦k≦85, 5≦m≦50, 2≦n≦60; k+m+n=100).
 16. The dielectric composition of claim 13, comprising one or more metal element selected from the group consisting of Ag, Cu and Ni in a total amount of 5 weight percent or lower.
 17. The dielectric composition of claim 13, comprising one or more metal oxide selected from the group consisting of CuO, V₂O₅ and WO₃.
 18. An electronic part comprising said dielectric composition of claim
 13. 19. The electronic part of claim 18 being a laminate type dielectric filter
 20. A dielectric composition for firing at low temperatures comprising a main composition of x.BaO-y.TiO₂-z1.Nd₂O₃-z2.La₂O₃ —z3.Sm₂O₃-t.Bi₂O₃ (x+y+z1+z2+z3+t=1; 0.100≦x≦0.250; 0.600≦y≦0.750; 0.010≦z1≦0.120; 0.000≦z2≦0.120; 0.000≦z3≦0.120; 0.010≦(z1+z2+z3)≦0.120; 0.065≦—t≦0.075; 0.35≦t/(z1+z2+z3+t) and B₂O₃ in an amount of 0.05 to 10 weight parts with respect to 100 weight parts of said main composition.
 21. The dielectric composition of claim 20, comprising one or more metal element selected from the group consisting of Ag, Cu and Ni in a total amount of 5 weight percent or lower.
 22. The dielectric composition of claim 20, comprising one or more metal oxide selected from the group consisting of CuO, V₂O₅ and WO₃.
 23. An electronic part comprising said dielectric composition of claim
 20. 24. The electronic part of claim 23 being a laminate type dielectric filter. 